@@ -26,6 +26,8 @@
#include <linux/crc32.h>
#include "nodelist.h"
+static struct lock_class_key jffs2_inode_info_sem_dir_key;
+
static int jffs2_flash_setup(struct jffs2_sb_info *c);
int jffs2_do_setattr (struct inode *inode, struct iattr *iattr)
@@ -277,6 +279,11 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
inode->i_mode = jemode_to_cpu(latest_node.mode);
+ /* Mirror lock class of inode->i_rwsem, see
+ * lockdep_annotate_inode_mutex_key.
+ */
+ if (S_ISDIR(inode->i_mode))
+ lockdep_set_class(&f->sem, &jffs2_inode_info_sem_dir_key);
mutex_lock(&f->sem);
i_uid_write(inode, je16_to_cpu(latest_node.uid));
@@ -439,6 +446,11 @@ struct inode *jffs2_new_inode (struct inode *dir_i, umode_t mode, struct jffs2_r
f = JFFS2_INODE_INFO(inode);
jffs2_init_inode_info(f);
+ /* Mirror lock class of inode->i_rwsem, see
+ * lockdep_annotate_inode_mutex_key.
+ */
+ if (S_ISDIR(mode))
+ lockdep_set_class(&f->sem, &jffs2_inode_info_sem_dir_key);
mutex_lock(&f->sem);
memset(ri, 0, sizeof(*ri));
@@ -30,6 +30,8 @@
#include "compr.h"
#include "nodelist.h"
+static struct lock_class_key jffs2_inode_info_sem_key;
+
static void jffs2_put_super(struct super_block *);
static struct kmem_cache *jffs2_inode_cachep;
@@ -60,6 +62,7 @@ static void jffs2_i_init_once(void *foo)
struct jffs2_inode_info *f = foo;
mutex_init(&f->sem);
+ lockdep_set_class(&f->sem, &jffs2_inode_info_sem_key);
inode_init_once(&f->vfs_inode);
}
We get a lockdep warning if we read a directory (e.g. ls) and fault a page on a regular file: [ 181.206207] mmaptest/392 is trying to acquire lock: [ 181.211066] (&f->sem){+.+.}, at: [<c01ff7d8>] jffs2_readpage+0x30/0x5c [ 181.217663] [ 181.217663] but task is already holding lock: [ 181.223477] (&mm->mmap_sem){++++}, at: [<c04928e8>] do_page_fault+0xa8/0x454 [ 181.230596] [ 181.230596] which lock already depends on the new lock. [ 181.230596] [ 181.238755] [ 181.238755] the existing dependency chain (in reverse order) is: [ 181.246219] [ 181.246219] -> #1 (&mm->mmap_sem){++++}: [ 181.251614] __might_fault+0x90/0xc0 [ 181.255694] filldir+0xa4/0x1f4 [ 181.259334] jffs2_readdir+0xd8/0x1d4 [ 181.263499] iterate_dir+0x78/0x128 [ 181.267490] SyS_getdents+0x8c/0x12c [ 181.271576] ret_fast_syscall+0x0/0x28 [ 181.275818] [ 181.275818] -> #0 (&f->sem){+.+.}: [ 181.280690] lock_acquire+0xfc/0x2b0 [ 181.284763] __mutex_lock+0x8c/0xb0c [ 181.288842] mutex_lock_nested+0x2c/0x34 [ 181.293272] jffs2_readpage+0x30/0x5c [ 181.297438] filemap_fault+0x600/0x73c [ 181.301690] __do_fault+0x28/0xb8 [ 181.305510] handle_mm_fault+0x854/0xec0 [ 181.309937] do_page_fault+0x384/0x454 [ 181.314188] do_DataAbort+0x4c/0xc8 [ 181.318181] __dabt_usr+0x44/0x60 [ 181.321999] 0xb6dffb02 Like with inode->i_rwsem, we recognize that this can never result in a dead lock, because we cannot page fault directory inodes and we cannot call getdents on non-directories. Thus we need different lockdep classes depending on the mode. This mirrors what lockdep_annotate_inode_mutex_key does to inodes. Link: https://www.spinics.net/lists/linux-rt-users/msg07644.html Signed-off-by: Helmut Grohne <h.grohne@intenta.de> Cc: Peter Zijlstra <peterz@infradead.org> --- fs/jffs2/fs.c | 12 ++++++++++++ fs/jffs2/super.c | 3 +++ 2 files changed, 15 insertions(+)